The optimal method for achieving deep sedation in this high risk group of patients is unclear. Propofol may accentuate airway collapse as patients become unresponsive to verbal stimulation (deep sedation). Recent studies suggest that propofol with midazolam and/or opioids may be synergistic in action and therefore the combined application of these drugs may permit smaller doses of each to be used and potentially lead to a reduction in risk of complications and in the dose of propofol needed while retaining the individual advantages of each compound. There is limited data evaluating the synergistic effect of propofol with midazolam and opioids in patients undergoing advanced endoscopy procedures. Ong and colleagues in a randomized controlled trial compared patient sedation and tolerance during ERCP using propofol alone or midazolam, ketamine and pentazocine (sedato-analgesic cocktail) for induction along with propofol for maintenance. Patient tolerance as assessed by visual analog scales by endoscopist and anesthetist were higher in the combination group. Paspatis et al reported higher dosage of intravenous propofol required in patients being sedated with propofol alone compared with that required in patients receiving oral dose of midazolam with propofol for ERCP procedures. In addition, the patients' anxiety levels before the procedure were lower in the combination group. The mean percentage decline in the oxygen saturation during the procedure was significantly greater in propofol alone group. However, these studies excluded patients deemed to be at a high risk for sedation related complications. Patients with ASA class 3 or higher were excluded, the mean BMI was less than 25, and included only patients at average risk for complications associated with sedation.